Conventionally, a water-discoloring sheet which comprises a sheet having provided thereon a porous layer containing a low-refractive-index pigment, and a means for fixing to a wall is disclosed.
The water-discoloring sheet becomes transparent upon liquid absorption in the porous layer, and color tone of an underlying layer can be perceived (for example, see Patent Document 1).
A broadcloth made from a polyester and cotton blend material (which is also known as “TC broad”) is disclosed as a substrate of the water-discoloring sheet. However, such a substrate involved the disadvantages that when a sheet is cut at the time of the production of the sheet, snag is generated, resulting in deterioration of productivity, and when the sheet is cut when used, snag is generated, resulting in impairing appearance of commercial products.
Further, the water-discoloring sheet has a waterproof layer comprising a polyethylene or the like provided on the back of the substrate. As a result, the sheet itself relatively increases its weight, and even though the sheet is fixed to a wall, there is the possibility that the sheet falls down by its own weight.
[Patent Document 1] Japanese Utility Model Registration No. 3099269